/Engine/Source/Runtime/Core/Public/Containers/ContainerAllocationPolicies.h
The inline allocation policy allocates up to a specified number of elements in the same allocation as the container. Any allocation needed beyond that causes all data to be moved into an indirect allocation. It always uses DEFAULT_ALIGNMENT.
template<uint32 NumInlineElements, int IndexSize, typename SecondaryAllocator> class TSizedInlineAllocator